﻿Shader "Custom/MeltLit"
{
    Properties
    {
        _Color ("Color", Color) = (1,1,1,1)
        _MainTex ("Albedo (RGB)", 2D) = "white" {}
        _Glossiness ("Smoothness", Range(0,1)) = 0.5
        _Metallic ("Metallic", Range(0,1)) = 0.0
        [Header(Melt)]
        [Space]
        _Melt("融解进度", Range(0, 1)) = 0
        _MeltEdgeSize("融解边缘宽度", Range(0, 1)) = 0
        [HDR]_MeltEdgeColor("融解边缘颜色", Color) = (1,1,1,1)
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 200

        CGPROGRAM
        // Physically based Standard lighting model, and enable shadows on all light types
        #pragma surface surf Standard fullforwardshadows

        // Use shader model 3.0 target, to get nicer looking lighting
        #pragma target 3.0

        sampler2D _MainTex;

        struct Input
        {
            float2 uv_MainTex;
        };

        half _Glossiness;
        half _Metallic;
        fixed4 _Color;

        half _Melt;
        half _MeltEdgeSize;
        half4 _MeltEdgeColor;

        // Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
        // See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
        // #pragma instancing_options assumeuniformscaling
        UNITY_INSTANCING_BUFFER_START(Props)
            // put more per-instance properties here
        UNITY_INSTANCING_BUFFER_END(Props)

        void surf (Input IN, inout SurfaceOutputStandard o)
        {
            // Albedo comes from a texture tinted by color
            fixed4 color = tex2D (_MainTex, IN.uv_MainTex);

            half ClipValue = color.a - saturate(_Melt - _MeltEdgeSize);
            ClipValue = step(ClipValue, 0);

            half ClipEdgeValue = color.a - _Melt;
            ClipEdgeValue = step(ClipEdgeValue, 0);
            color.rgb = lerp(color.rgb, _MeltEdgeColor.rgb, ClipEdgeValue * (1 - ClipValue));

            clip((1 - ClipValue) - 0.5);

            o.Albedo = color.rgb * _Color.rgb;
            // Metallic and smoothness come from slider variables
            o.Metallic = _Metallic;
            o.Smoothness = _Glossiness;
            o.Alpha = color.a;
        }
        ENDCG
    }
    FallBack "Diffuse"
}
